Combination slotting and milling tool



June 24,1969 c. w. HIGHBERG ET AL COMBINATION SLOITING AND MILLING TOOLm 2 0 TG f NR 0 O E 4. mm 3 men S t W ES h LE S RM AA CJ Y B w 2 2 F 7 69 1 G 6 h C F r a M d e l 1 F v AGENT C. 'W. HIGHBERG ET AL COMBINATIONSLOTTING AND MILLING TOOL Sheet 3 of 2 June 24, 1969 Filed March a. 1967DIRECTION OF TRAVEL p CENTER LINE DISTANCE INVENTORS CARLE W. HIGHBERGJAMES B. SPEIRS United States Patent 3,451,721 COMBINATION SLOTTING ANDMILLING TOOL Carle W. Highberg, Murray Hill, and James B. Speirs,Paramus, N.J., assignors to Engelhard Hanovia, Inc., Newark, N..I., acorporation of New Jersey Filed Mar. 6, 1967, Ser. No. 621,013 Int. Cl.E21c 25/18 US. Cl. 299-89 2 Claims ABSTRACT OF THE DISCLOSURE Thepresent invention deals with a combination slotting and milling tool forslotting and milling surfaces of refractory materials such as concretepaving, asphalt paving, brick, granite, slate, etc., having acylindrical spool- BACKGROUND OF THE INVENTION In the marking ofconcrete paving of highways with reflecting surfaces or lines, e.g., forthe purpose of outlining driving lanes, or the like, it has been knownto cement or otherwise secure projecting reflecting particles or beadson the surface of a substrate strip material, e.g. metal strip, and tocement the strip to the surface of the highway. Such a reflectingmarking means for highways presents a problem in that the reflectingstrip material is raised on the surface of the highway and becomesdamaged or dislodged especially by snowplows or other heavy vehiclespassing thereover. Since, of course, the surface of the highway is notalways smooth it does not always conform to the bonding surface of thestrip material so that the strip is not always uniformly securely bondedto the roadway.

I order to overcome such disadvantages, it has been thought to recessgrooves in the highway surface and to partly recess the reflectorbearing strip into the recess grooves. However, grooving the highway asuflicient depth to anchor the strip material therein is an expensiveand tedious matter since, in such case, a large quantity of the roadmaterial has to be removed by milling to provide grooves of sufficientwidth and depth to anchor the inlaid strip. The invention contemplatesthe secure anchoring of a raised reflecting strip on a roadway by aminimum removal of the road material, whereby the strip material isanchored mainly at its opposite longitudinal edges, which are formed toengage a pair of parallel slots cut into the road surface and with theroad material, e.g. concrete, between the slots being milled preferablysufficiently only to provide a shallow groove for the smoothening of theroad material between the parallel slots to more uniformly engage andmate with the undersurface of the strip material for improved bonding,such as cementing, of the strip to the roadway.

SUMMARY OF THE INVENTION It is herein contemplated to provide acombination slotting and milling tool for slotting and millingrefractory surfaces, which comprises the combination of a cylindricaldrum having a pattern of spaced abrasive means raised on and about thecylindrical outer surface of the drum, and a pair of laterally spacedcutting discs each being mounted co-axially of the drum at each end ofthe drum and each being of greater diameter than the drum and having aplurality of abrasive means circumferentially spaced from each other andmounted on the peripheral surfaces of the discs.

THE \DRAWINGS FIGURE 1 is an elevational end view of the combinationslotting and milling tool according to the invention,

FIGURE 2 is a cross-sectional view along lines 22 of FIGURE 1,

FIGURE 3 is an isometric view of a component of the tool of theinvention,

FIGURE 4 is a fragmentary cross-sectional view of a concrete roadwayslotted and milled with the tool of the invention, and

FIGURE 5 is a schematic view of the tool showing concrete removal.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings,FIGURES 1-3 illustrate the combination slotting and milling tool of theinvention. The tool comprises a cylindrical metal drum 2 having inwardlydirected annular flanges 4 and 6 with one at each open end thereof andwhich may be integral with the drum or welded thereto and which defineopenings 5 and 7, respectively. The outer surface of the drum isprovided circumferentially thereof with a pattern of recesses 8, and aplurality of abrasive inserts 10 are each suitably mounted in one of therecesses as by brazing or welding. The inserts are composite insertshaving a metal base 12 with a metal slug 14, for milling purposes,impregnated with abrasive particles and bonded to the metal base 12, asby silver brazing, with the metal base 12 seated in the recess 8. Theflanges 4 and 6 are each provided with circumferentially spaced bores"16, e.g. threaded bores formed therethrough and arranged substantiallyas illustrated by FIGURE 3. l

A pair of centrally apertured cutting wheels or discs 18 and 20, ofgreater outer diameter than the drum 2 are each provided with circularcentral apertures 19 and 21, respectively, preferably coinciding indiameter with the openings 5 and 7, and each disc is mounted one at eachend of the drum 2 as illustrated by FIGURE 2. Each cutting disc isprovided with circumferentially spaced apertures 22 therethrougharranged to coincide with bores :16 in the flanges 4 and 6. A circularsecuring plate 24 having a central opening 26 with a short annularshoulder 28 defining the opening 26 and extending outwardly of the plate24 co-axially of the opening 26 is mounted adjacent the disc 18 with theouter surface of the shoulder inserted in abutment with the walls ofopening 5 of flange 4 and the walls of aperture '19 of disc 18 and withthe plate in abutment with the outer side of disc 18. The plate 24 isprovided with circumferentially spaced bores 30 therethrough arranged tocoincide with flange bores 16 and disc apertures 22. Securing means,e.g. screws or bolts 32, are each engaged with a bore 30, aperture 22and flange bore 16 to secure the plate 24 and disc 18 to drum flange 4.

A substantially cylindrical hub member 34 is mounted in opening 7 andaperture 21 and in abutment with the walls of opening 7 and aperture 21of disc 6 and a portion 35 of the hub extends into the drum 2. The hubmember 34 has a co-axial shaft bore 36 formed therethrough and a flange38 at one portion thereof with the flange positioned in abutment withdisc 20. The flange 38 is provided with bores 40 formed therethrough andarranged to coincide with apertures 22 and bores 16. Securing means,e.g. screws or bolts 42, are each engaged with a bore 40 of flange 38,aperture 22 and bore 16 of drum flange 6 to secure the hub 34 to thedrum 2.

Each of the discs 18 and 20 is provided with a plurality of abrasivemeans 44 mounted on the peripheral surfaces thereof andcircumferentially spaced from each other. The abrasive means 44 arecomposite bodies having a metal base 46 with a metal slug 48, forcutting purposes, impregnated with abrasive particles bonded to themetal base 46. The abrasive particles may be particles oftungsten-carbide or diamond grit depending on the material to be slottedor milled, preferably, the abrasive means 44, as well as the abrasivemeans hereinbefore described, comprise a metal slug impregnated withdiamond abrasive material.

FIGURE 3 illustrates the advantageous pattern of spaced abrasive means10 on the surface of drum 2. In order to effect uniform milling of agroove from one side to the other and to economize on the abrasivematerial, especially when diamond material is employed as the abrasive,the spaced inserts are arranged in a pattern of rows spacedcircumferentially of the drum with the inserts of one row A staggeredrelative to the inserts of another adjacent row B, and the rows beingdirected at an acute angle from one end of the drum to the otherrelative to the drum axis. Also, the number and abrasive surface areasof inserts 10 on the drum 2 are preselectively proportioned relative tothe cutting members 44 on discs 18 and 20 so that when both the discsand drum are in contact with the refractory material, e.g. concrete,there will be approximately equal wear of the cutting and millingabrasive means whereby the relative depth of the cuts remainsubstantially the same throughout the life of the tool. The rows ofinserts A and B, etc., on drum 2 are spaced from each other a greaterdistance than the spacing between abrasive means 44 on discs 18 and 20.For example, each disc 18 and 20. For example, each disc 18 and 20 maybe about 8" in diameter with about thirty six abrasive means 44 aboutits periphery, while the drum 2 may be about 6" to 7 in diameter withabout sixteen rows of inserts about its circumference.

Having provided the tool in accordance with the invention, the tool isdriven by a motor means (not shown) connected to a shaft threaded at itsfree end and mounted through hub bore 36 and secured by a bolt 52. Thus,when the shaft 50 is rotated, the entire tool including drum 2 and discs18 and 20 are likewise rotated at advantageous speeds for the cuttingand milling.

FIGURE 4 illustrates, as a cross-sectional view in the direction of toolmotion, one type of laterally spaced slots 54 and 56 and intermediategroove surface 58 formed by the tool. For application to the illustratedslots and groove, the metal insert 60, carrying on .a portion of itssurface a layer 62 of reflecting particles or beads has a substantiallyU-shaped cross section with the legs 64 and 66 of the U-shaped metalsubstrate strip engaging and preferably cemented in the slots 54 and 56.The metal insert with its reflecting particles extends a small distanceabove the road surface when in place, as illustrated by FIGURE 4, andthe reflecting surfaces, projecting less than uncovered metal portionsof the insert, are readily visible to oncoming motorists without beingdamaged by impact.

In operation, a conventional concrete diamond sawing machine with thetool rotating was caused to first penetrate the concrete without movingthe tool horizontally, the tool next was moved horizontally in thedirection of automotive traflic flow and then finally was raised fromthe concrete. Total time for such concrete removal steps was less than aminute.

An example of the preselection of areas of abrasive members on disc anddrum for approximately equal wear of the tool designed in accordancewith this invention for slotting and milling concrete is given below.

EXAMPLE Grinding abrasive elements were attached to the discs or sawsand the drum with 4;" thick hot-pressed diamonds in a matrix chiefly ofiron, e.g. steel with minor amounts of carbon and manganese on a A"thick hotpressed backing chiefly of iron. Surface dimensions for eachabrasive elements were /2" x A". In accordance with the saw and drumdimension given below, 36 such abrasive elements were used on each sawand 72 such abrasive elements were used on the drum.

Cuts in the direction of automotive traffic using a tool in accordancewith FIGURES 1-4 were made for a A" full depth removal of concrete witheach saw blade for a center line to center line full depth distance of5" as shown in FIGURE 5. FIGURE 5 is a schematic end view of the toolshowing the initial application of the tool at the left in broken linesfor the beginning of the cutting and milling and showing at the right anend of the tool in solid line at the completion of the cutting andmilling for the concrete removal to inlay a reflector. Full depthconcrete removal takes place between the center lines C and D andadditional segment volume removals occur as indicated at E and F inFIGURE 5. Two conventional concrete saws of 4 radius were used for theslotting, the abrasive material being 2040 grit size diamonds inconcentration of 30 carats per cubic inch embedded in the matrix to asurface depth of /8". The same size and concentration of diamonds withthe same matrix was used for the .abrasive on the drum surface. The drumhad a radius of 3%" to the grinding surfaces in order to remove /8" ofconcrete, full depth removal of the concrete with the drum also takingplace for a distance of 5".

The volume of concrete to be removed by the described tool in inlayingeach reflector was calculated .as follows:

By each saw (1) Full depth cuts:

depth x A" Width X 5" length=0.938 in. (2) Segment volume before andafter full depth cuts:

2.38 in? segment area x A width=0.595 in.

By the drum 1) Full depth cuts:

4; depth x l -W with x 5 length:0.938 in. 2) Segment volume before andafter full depth cuts:

0.18 in. segment area x 4% width=0.82 in.

Accordingly, the volume to be removed by drum cutting was 3.67 in? andby cutting with each saw was 1.53 in. or a ratio of 2.4: l. A tool wasconstructed using a ratio of drum cutting surface to saw cutting surfaceof 2:1, taking into account that plunging entry of saws is expected tocause additional saw wear.

Various modifications of the invention are contemplated within the scopeof the appended claims.

What is claimed is:

1. A combination slotting and milling tool comprising a cylindricaldrum, a plurality of abrasive means mounted on and extending outwardlyof the peripheral surface of the drum in spaced relationship with eachother, said spaced abrasive means being arranged in rows spaced for eachother circumferentially of the drum, a pair of circular disc membershaving an outer diameter greater than the outer diameter of the drumeach mounted on one end of the drum coaxially thereof, a plurality ofabrasive means mounted on the peripheral surface of each disc and spacedfrom each other circumferentially of the disc, the said rows of abrasivemeans being spaced from each other a greater distance than the spacingbetween the abrasive means mounted on said discs, and said rows eachbeing directed from one end of the drum to the other at an acute anglerelative to the drum axis.

2. A combination slotting and milling tool according to claim 1, whereinsuch abrasive means comprises a metal slug impregnated with diamondparticles.

(References on following page) 5 References Cited UNITED STATES PATENTS1 ,965,384- 7/1934 Legge 125-5 2,000,7-72 5/1935 McGill 51--206.42,032,362 3/1936 Herman 51-2064 5 3,162,187 12/ 1964- Christensen 125-156 3,324,603 6/1967 Niemiec 51-206.4 3,338,230 8/1967 Lindblad 125-15HAROLD D. WHILEHEAD, Primary Examiner.

US. Cl. X.R. 51-181, 206; 125-5

